Tag: forensics

You are what you eat—that’s true even after your bones have spent 200 years buried in the dirt. A new study using old bones from 18th century British sailors confirmed the naval diet: lots of biscuits, more protein than the average landlubber, and the same damn things sailors ate for the previous 200 years.

The Victualing Board actually kept meticulous records of a sailor’s official rations: 1 lb of bread and 1 gallon of beer per day (!), plus 1 lb of pork twice a week, 2 lbs of beef twice a week, or butter and cheese the other three days. But when the going got tough out in the middle of watery nowhere, did sailors actually get their rations? Yes, it seems, based on an analysis of nitrogen isotopes extracted from the bones of 80 sailors. The elevated levels of nitrogen suggested that sailors did get as much beef and pork as the Victualing Board recorded. And despite being at sea, they didn’t seem to eat much fish.

Their findings imply that vultures can take much longer—37 days instead of 24 hours—to find a body than the carcass of a pig left in the wilderness, which is what previous studies in the Texas facility have used. On the other hand, vultures can also pick clean, or skeletonize, a body much faster than we’d thought: it took just 5 hours instead of the expected 24. The scientists also tracked where the vultures spread the body parts that they didn’t consume, as they kept visiting the body over the following five months, which will be useful in figuring out how far away a body might be if a bone or other part is found by itself in future forensic investigations.

In the dreams of crime scene investigators, no doubt, they can feed a piece of hair into a machine and see a reconstruction of what the owner looks like. There’s a hint of that fantasy in the news that Dutch scientists have developed a test intended help police tell from a crime scene DNA sample the color of a suspect’s eyes. This information is gleaned from examining six single nucleotide polymorphisms, small genetic markers that are used in DNA fingerprinting, and could potentially help steer investigations when there are few other leads on a suspect and there is no match in police DNA databases. But the test, which can tell whether someone has blue, brown, or indeterminate (which encompasses green, hazel, grey, etc.) eyes with an average of 94% accuracy, doesn’t seem to have been tested outside of Europe, which raises questions about how well it would work in populations with greater diversity. It’s also a little hard to feature how you could bring this information to bear in a vacuum of other details—you’d want to avoid hauling someone in just because they looked suspicious and have the same eye color as the readout for the perp. At the moment, the test is not accurate enough to be introduced as evidence in court, which could be a bad thing or a good thing…depending on how many Philip K. Dick novels you’ve read.
Image courtesy of wetwebwork / flickr

You wouldn’t know it from crime shows, but DNA evidence can have more holes in it than Swiss cheese. And the Amanda Knox murder appeal, in which the DNA evidence that led to Knox and former-boyfriend Sollecito’s convictions in 2009 was thrown out, provided a great example of how a powerful tool, when used incompetently, can be worse than useless.

What’s the News: While you may be able to hide your age with makeup and plastic surgery, don’t think that your deception is foolproof. Researchers have now developed a technique to ascertain your age to within five years using only your saliva. The new method, published in the journal PLoS One, could someday be used by forensic experts to pinpoint the age of crime suspects.

What’s the News: You might think that identical twins have an advantage when it comes to crime—with the same DNA, who could tell them apart? But new research with a squad of scent-trained Czech police dogs reveals that even identical twins have their own individual smells, even if they live in the same house and eat the same food.